Wireless telegraphy.



1. 0. wmxmsQ WIRELESS TELEGRAPHY. APPLICATION FILED JULY 28. 1915.

1,224,343. Patented Maj1,1917. I

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WITNESSES: J. 0. M; wn/Vs ATTORNEYS.

UNITED STATES PATENT OFFICE.

JAMES O. WATKINS, OF SAN FRANCISCO, CALIFORNIA. ASSIGN OR TO FEDERALTELE- GRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OFCALI- FORNIA.

WIRELESS TELEGRAPHY.

Patented May 1, 1917.

Application filed July 28, 1915. Serial No. 42,301.

To all whom it may concern:

Be it known that I, Janus O. YATKIXS, a citizen of the United States,and a resident of San Francisco, county of San Francisco. State ofCalifornia, have invented certain new and useful Improvements inWireless Telegraphy, of which the following is a specification.

The invention relates to a receiving system for wireless telegraph andespecially to a device adapted to be used in said system.

An object of the invention is to provide an apparatus by means of whichcontinuous electrical oscillations of high frequency are converted intocontinuous oscillations of lower frequency.

The invention possesses other objects and advantageous features, some ofwhich, with the foregoing, will be set forth at length in the followingdescription, where I shall outline in full that form of the inventionwhich I have selected for illustration in the drawings accompanying andforming part of the present specification. In the drawings I have shownonly one specific form of the apparatus of my invention, but it is to beunderstood that I do not limit myself to such form, because my inventionmay be em-' bodied in a multiplicity of forms. each being a species ofmy said invention. It is also to be understood that by the claimssucceeding the description of m invention, I desire to cover theinvention in whatever form it may be embodied.

Referring to said drawings:

Figure l is a top or plan view of one form of the apparatus of myinvention.

Fig. 2 is a vertical section taken on the line A-A Fig. 1.

Fig. 3 is a diagrammatic representation of a wireless telegraphyreceiving circuit,

showing the apparatus of my invention arranged therein.

Fig. 4 is a diagrammatic illustration of the effects produced by theoperation of the apparatus.

The frequency of the oscillations of the electric impulses in a wirelesstelegraphy system employing substantially continuous undamped waves, isso high that they cannot be directly utilized to operate electromagnetic instruments, such as telephone reccivcrs, toproduce audiblesignals. The.

frequency .of the received oscillations is above the limits ofaudibility and to be received by the ear, the frequency must be reducedto within the limits of audibility. This has been accomplishedheretofore by arranging an interrupter and a condenser in thereceivingcircuit, the condenser being chargedby' the high frequencyoscillations during the time that the interrupter is closed. anddischarging with a surge through the telephone receivers when theinterrupter is open.

In accordance with the present invention, the high frequency current isconverted into a low frequency current. and the telephone receivers areoperated by the latter current, The receiving circuit is opened andclosed at a frequency which may be made to approach synchronism with thefrequency of the received oscillations, thereby producing a low beatfrequency. The regularity of the beat frequency gives a musical note tothe received signals and the nearer the frequency of interruptionapproaches the frequency of the incoming waves, the lower will be thenote. In Fig. I I have shown diagrammatically the incoming undampedoscillations of high frequency 2. The frequency of interrimtiou issomewhat less than the frequency of the,- waves, resulting in beatfrequency oscillations3, which are of much lower frequency than theincoming waves.

The apparatus of my invention comprises a suitable base 4, upon which ismounted a metallic standard 5. Secured to the standard 5 is a holder 6having a resilient shank 7. Horizontally disposed in the holder 6 is abar 8 which constitutes the base of the string or wire holder. Passingthrough the standard 5 is an adjusting screw 9 which bears against theholder 6. and by turning the screw the position of the bar 8 may bevaried.

Secured to the bar at one end is a block 12 to which one end of the wire13 is secured, and at the other end of the bar is a slotted post l-lthrough which the wire passes. The other end of the wire is fas tened tothe key 15 engaging in the end of the bar. Adjacent post ll is a secondslotted post 16 having a roller 17 under which the wire passes arrangedin the slot. Between the posts and guided thereby is a means for varyingthe tension f the wire. This means consists of a wedge shaped block isguided by the posts 14 and 16 and being movable against the wire by thethumb screw 19 passing through the bar 8.

The wire is vibrated by means of a smooth edged disk 21 which rotates ininterrupted engagement with the wire. The point of contact of the diskand wire is arranged -with relation to the wire. so that it occurs at ananti-node of the desired harmonic. The wire adheres to the disk as itrotates and is stretched out until the curvature of the disk allows itto slip back to its former position, where it is again caught by thedisk and the action repeated. Vibration of the wire will, therefore, bemaintained and the wire contacts with the disk at the frequency of itsvibration. The axis of the disk preferably lies in the same horizontalplane as the wire and the disk is rotated in such direction that thatside of the disk which contacts with the wire moves upward.

The disk is placed in contact with the wire at a. point midway betweentwo successive nodes or in other words, at a point exactly one-half thedistance between two nodes. Means are, therefore, provided for adjustingthe point of contact with relation to the adjacent nodal points. This'adjust ment is accomplished by means of the sliding bridge 22 whichrests on the bar 8 and which engages the wire. A thumb screw 23 isprovided for sliding the bridge along the bar 8. After the properposition of the bridge is found which produces the proper distancebetween the disk and the effective end of the wire, tuning may beaccomplished by varying the tension of the wire by means of the screw 19or by var ing the pressure of the wire against the dislz by means of thescrew 9. The disk is rotated by a motor 24 which is insulated from thewire 13.

I have found that the adjustment of the apparatus usually holds betterif the disk is not rotated exactly at right angles to the wire, butpreferably at an angle of about with respect thereto.

The device is placed in the receiving circuit in series with thetelephone receivers 25 the wire 13 being connected in the circuit bymeans of the binding post 26 and the disk being provided with-a brush 27connected to the other side of the circuit. The incoming high frequencycurrents pass through the disk and wire in series and are interrupted atthe frequency of the harmonic producing a beat wave of low frequencywhich passes through the telephones.

The disk, which is preferably made of phosphor bronze, bears lightlyagainst the wire, which is preferably of steel. The edge of the disk,which is preferably rounded, should be very carefully polished withcrocus cloth and should be kept clean and dry in order that thefrequency of interruptions may be constant. It is essential also thatthe edge of the disk be concentric with its axis of revolution.

By making the frequency of vibration of the wire equal to the frequencyof the oscillations, the device may be employed as a rectifier.

I claim:

1. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate and a smooth edged r0- tatable disk incontact with said wire said wire and said disk being connected in seriesin said circuit. 1

2. In an apparatus of the character described, an electric circuit, awire mounted to vibrate and a smooth edged rotatable disk in contactwith said wire at an antinode said wire and said disk being connected inseries in said circuit.

3. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate and a smooth edged r0- tatable disk inlight contact with said wire at an antinode adjacent the end of the wiresaid wire and said disk being connected in series in said circuit.

4. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire and means for varying the tension of said wiresaid wire and said disk being connected in series in said circuit.

5. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth faced rotatable disk incontact with said wire at an antinode and means for varying the tensionof said wire said wire and said disk being connected in series in saidcircuit.

6. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire and means for varying the pressure of the wireagainst the disk said wire and said disk being connected in series insaid circuit.

7. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire at an antinode and means for var ing the pressureof the wire against the dis said wire and said disk being connected inseries in said circuit.

8. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire and means for varying the vibratory length ofsaid wire said wire and said disk being connected in series in saidcircuit.

9. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire at an antinode and means for varying thevibratory length of said wire said wire and said disk being connected inseries in said circuit.

10. In an apparatus of the character described, an electric'circuit, astretched wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire at an antinode adjacent one end of the wire andmeans at the same end of the wire for varying the vibratory length ofthewire said wire and said disk being connected in series in said circuit.

11. In an apparatus of the character described, an electric circuit, astretched Wire mounted to vibrate, a smooth edged rotatable disk incontact with the wire at an antinode, means for varying the tension ofsaid wire and means for varying the pressure of said wire against thedisk said wire andsaid disk belng connected in series in said circuit.

12. In an apparatus of the character described, an electric circuit, astretched wire mounted to vibrate, a'smooth edged rotatable diskincontact with said wire at an antinode,

- means for varying the vibratory length of said wire, and means forvarying the tension of said wire said wire and said disk being connectedin series in said circuit.

13, .In an apparatus of the character described, an electric circuit, astretched Wire mounted to vibrate, a smooth edged rotatable disk incontact with said wire at an antinode means for varying the vibratorylength 01% said wire and means for varyin the pressure of the wireagainst the disE said wire and said disk being connected in series insaid circuit.

14. In an apparatus of the character described, an electric circuit, ahorizontally disposed stretched wire mounted to vibrate and a smoothedged disk rotatable about a horizontal axis lying in the samehorizontal plane as the wire, in contact with said wire at an antinodesaid wire and said disk being connected in series in said circuit.

In testimopf whereof, I have hereunto set my hand at onolulu, Territoryof Hawaii, this 10th day of June, 1915.

JAMES O.- WATKINS.

In presence of- G. A. CUNNINGHAM, W. Y. Nommr.

